The present invention relates to networked computer systems and in particular to the selection of a server for desired information based on performance.
Networks, such as the Internet contain information that a user desires to obtain. The information is contained in files that may be specified by uniform resource locators (URLs) which are essentially addresses which specify the computer and the location of the file on that computer. Many times, several computers, referred to as servers will have the same file available for retrieval by a user. Each such file has a different URL. In some cases, multiple servers may be connected together to appear as a single site and have several individual servers having the same file for increased overall throughput. In such cases, a manager of the servers transparent to the user system selects which individual server or servers should provide the file given a client/user request. The manager may select the server to balance the load between the servers. However, most files on the Internet are located on separate servers and are identified with separate URLs.
When a user tries to access a file, a site is selected, and the file transfer is requested through a browser when a user clicks on highlighted text or image which is associated with the URL, or types in the URL directly. This link identifies only one site, which may be very busy. The user will usually select a site which is geographically closest to the user. This may or may not be the best choice. There is no easy ability for a user to select a different site, other than to stop the transmission of the file after noticing that it is taking a long time, then searching for a different site with the same file and initiating a new transfer. Some sites do offer multiple sites from which to obtain the information, but the user still must make the decision as to which site to use, and if not satisfied, stop the transmission and start over by selecting another site.
A further method of determining which site might respond faster involves the use of a program which will ping a group of selected sites to see which will respond the fastest. A ping is a well known method of sending a message to a server, essentially asking xe2x80x9care you there?xe2x80x9d The server will then respond that they are there. While this gives a good indication of the length of time for a download of a file to begin, it provides little information regarding the speed at which such a download will proceed. There is a need for an easier and more informative way to determine which server will provide the fastest download of a file. There is also a need for downloading information or files more quickly.
Downloading of files is optimized based on which of multiple locations is most efficient in providing the files. In one implementation of the invention, portions of a file are downloaded from different servers, and performance data such as a bit rate for each site is used to then select the optimal server to complete the download.
In a further embodiment, an applet intercepts the request for the file from the browser and determines the best server to provide the file. When the request is intercepted, the applet reads a list of available file transfer protocol (ftp) locations from which to download the file. The list may be hidden text in an hypertext markup language (HTML) page, or may actually be provided by a link on a server. The applet or other type of program then may ping each site to prioritize the list based on shortest response time. A first portion of the file is downloaded from one site, and throughput measurements tracked. Using a reconnect internet protocol command to identify where the first download ended, a second portion of the file is downloaded from the next site on the list, again with throughput measurements tracked. This process is repeated for further portions of the file, and the location with the best throughput is selected to complete the file transfer. In still further embodiments, a same portion such as the first portion is read from each server to ensure consistent throughput measurements.
In yet a further embodiment of the invention, the throughput of the finally selected server is tracked as the file is downloaded. If the throughput drops below a desired throughput, the next best server is selected from the previous list, or the selection and tracking process is started again to determine if a faster server has become available due to changes in demand on the servers.
The present invention provides improved information regarding the best server from which to obtain a desired file, and the ability to download files quickly.